Flue gas monitoring and dynamic spiking for sulfur trioxide/sulfuric acid

• US 8,021,617 B2
• Filed: 10/27/2009
• Issued: 09/20/2011
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Clean Air Engineering, Inc.
• Original Assignee: Clean Air Engineering, Inc.
• Inventors: Evans, Scott A., Roesler, Daniel H.
• Primary Examiner(s): Gakh; Yelena G
• Assistant Examiner(s): Adams; Michelle
• Application Number:
  US12/606,454
• Publication Number:
  US 20110097809A1
• Time in Patent Office: 693 Days
• Field of Search: None
• US Class Current: 422/93
• CPC Class Codes: G01N 2021/3595 using FTIR
• CPC Class Codes: G01N 33/0042 for SO2, SO3
• CPC Class Codes: Y10T 436/156666 Sulfur containing
• CPC Class Codes: Y10T 436/18 Sulfur containing
• CPC Class Codes: Y10T 436/186 Sulfur dioxide

Abstract

Systems and methods are disclosed for measuring sulfur trioxide/sulfuric acid content of flue gas. A probe is provided that extracts two separate lines of gas samples simultaneously from the flue gas. One of the two lines is dynamically spiked with a known quantity of sulfur trioxide, preferably generated in the probe. A comparison of sulfur trioxide/sulfuric acid content measurements from the spiked and unspiked lines helps identify and adjust for inherent biases in the measuring system. Also disclosed are catalyst structures and methods for use thereof for generating sulfur trioxide at known concentration.

Claims

1. A system for monitoring sulfur trioxide/sulfuric acid levels in an emission stream comprising sulfur trioxide and water vapor flowing through an exhaust, the system comprising:

a probe positionable adjacent to the exhaust to be able to extract essentially simultaneously a first supply of sample gas from the exhaust and a second supply of sample gas from the exhaust, wherein the second supply of sample gas is separate from the first supply of sample gas, the probe comprising the following elements housed within an outer probe shell;

(i) an unspiked line for carrying the first supply of sample gas,

(ii) a spiking line for carrying the second supply of sample gas,

(iii) a catalyst for converting SO₂ gas to SO₃ gas,

(iv) an inlet line for supplying SO₂ gas of a known quantity to the catalyst,

(v) a heating coil positioned adjacent to the catalyst,

(vi) a thermocouple,

(vii) a carrier line for adding SO₃ gas generated at the catalyst to the second supply of sample gas in the spiking line to create a spiked gas, and

(viii) an outlet line for carrying the spiked gas to a connector to measuring equipment, the connector to the measuring equipment, and the measuring equipment in the form of the means for measuring as claimed below, being located outside the probe;

the system further comprising;

a condenser for condensing sulfuric acid in the first supply of sample gas carried by the unspiked line;

a condenser for condensing sulfuric acid in the spiked gas carried by the outlet line;

means for measuring sulfuric acid content in the first supply of sample gas carried by the unspiked line; and

means for measuring sulfuric acid content in the spiked gas carried by the outlet line;

whereby the system is configured such that a comparison of the measuring of the sulfuric acid content in the first supply of sample gas carried by the unspiked line with the measuring of sulfuric acid content in the spiked gas carried by the outlet line can help validate the system.

2. The system of claim 1, wherein the heating coil is capable of heating the catalyst to a temperature above 750°

F.